Contracting Office Address

NASA/Goddard Space Flight Center, Code 210.S, Greenbelt, MD 20771

Description

LRO RF Communications Reference Baseline dated June 2, 2005

This document is intended to inform interested vendors of the current baseline architecture for the Lunar Reconnaissance Orbiter mission communication system. This document describes the current project understanding of LRO's mission communications as a result of the project's previous RFI process. This is not a request for additional RFI responses, nor is this a request for vendor proposals. No procurement action will be taken as a result of this document's release.

The LRO Project intends to initiate three separate competed procurement efforts to acquire the flight components for the LRO Spacecraft Communication System. These procurements will consist of the S-Band TT&C Transponder, the High-Rate Ka-Band Modulator, and the Ka-Band Traveling Wave Tube Amplifier (TWTA).

LRO shall provide tracking, telemetry and command functions using S-Band. LRO shall provide high rate mission data return at Ka-band. At a minimum, LRO will perform a 30 minute TT&C pass every lunar orbit (approximately every 2 hours). LRO will perform up to 4 high rate Ka-band downlinks in a 24 hour period. The high rate downlinks may be adjacent passes.

S-Band TT&C Subsystem

LRO's S-Band TT&C subsystem architecture consists of a STDN transponder and associated diplexer, switches and RF network to connect the transponder to the omnidirectional and high gain antennas. Command decryption (if required) can be accommodated internal to the transponder, or through the use of a standalone command decryptor in-line between the transponder receiver and the S-Band comm. card in the C&DH processor. The transponder shall provide the following modes: